Impaired scaling of preparatory postural responses to repeated balance perturbations in Parkinsonian patients with comorbid white matter disease.

Background: Postural instability may result from altered sequencing of automatic motor programs for anticipatory postural corrections and/or impaired motor learning in Parkinson Disease (PD) patients. Comorbid white matter disease is a major determinant of axial motor impairment, leading to poorer stability than nigrostriatal dopaminergic denervation per se.

Objective: To assess differences in anticipatory control of postural stability function between subjects affected by PD with comorbid leukoaraiosis (LPD), idiopathic Parkinson disease (IPD) and elderly healthy subjects (EHS) as control group.

Role of brain hemispheric dominance in anticipatory postural control strategies.

Most of the cerebral functions are asymmetrically represented in the two hemispheres. Moreover, dexterity and coordination of the distal segment of the dominant limbs depend on cortico-motor lateralization. In this study, we investigated whether postural control may be also considered a lateralized hemispheric brain function.

Differential effects of acute cortisol administration on deep and shallow episodic memory traces: a study on healthy males.

We aimed at investigating rapid effects of plasma cortisol elevations on the episodic memory phase of encoding or retrieval, and on the strength of the memory trace. Participants were asked either to select a word containing the letter "e" (shallow encoding task) or to judge if a word referred to a living entity (deep encoding task). We intravenously administered a bolus of 20mg of cortisol either 5 min before encoding or 5 min before retrieval, in a between-subjects design.

More than at the neuromuscular synapse: actions of botulinum neurotoxin A in the central nervous system.

Botulinum neurotoxin type A (BoNT/A) is a metalloprotease that produces a sustained yet transitory blockade of transmitter release from peripheral nerve terminals. Local delivery of this neurotoxin is successfully employed in clinical practice to reduce muscle hyperactivity such as in spasticity and dystonia, and to relieve pain with long-lasting therapeutic effects. However, not all BoNT/A effects can be explained by an action at peripheral nerve terminals.

Meaningful improvement in walking performance after Botulinum neurotoxin A (BoNT-A) in chronic spastic patients.

Background: Botulinum neurotoxin A (BoNT-A) may reduce lower limb spasticity but its role in improving walking ability remains to be established.

Objective: To investigate the efficacy of simultaneous BoNT-A injections into several targeted spastic muscles of different joints on gait speed and on functional gains in gait performance in chronic stroke and MS patients.

Methods: Twenty patients affected by stroke or multiple sclerosis were tested before, one and three months after BoNT-A administration.

Predictors of long-term recovery in complex activities of daily living before discharge from the stroke unit.

Background And Purpose: There is a need for individuating those post-stroke patients who may benefit from an optimal and customised rehabilitation plan aiming at early reintegration in community life participation. This study investigated whether the gain of independence in complex Activities of Daily Living (ADL) may be predicted before the discharge from the stroke unit using simple bedside determinants.

Methods: In 104 first-ever stroke patients with no previous disability, ten determinants at 10 days after stroke were selected.

Beyond muscular effects: depression of spinal recurrent inhibition after botulinum neurotoxin A.

The natural target of the botulinum neurototoxin type A (BoNT-A) is the neuromuscular junction. When injected into a muscle, BoNT-A is internalized by motoneurone terminals where it functions as an endopeptidase, cleaving protein components of the synaptic machinery responsible for vesicle docking and exocytosis. As a result, BoNT-A induces a characteristic flaccid paralysis of the affected muscle.

Relationship between the modified Rankin Scale and the Barthel Index in the process of functional recovery after stroke.

Objective: The modified Rankin Scale (mRS) and the Barthel Index (BI) are the most common clinimetrical instruments for measuring disability after stroke. This study investigated the relationship between the BI and the mRS at multiple time points after stroke. The BI, which is a widely used instrument for longitudinal follow-up post-stroke, was used as reference to determine the effect of time on the sensitivity of the mRS in differentiating functional recovery.

Cortisol-induced effects on human cortical excitability.

Background: Cortisol may fulfill all criteria for a neuromodulator. However, it is not known whether it may rapidly influence motor system activity in humans.

Objective: Circulating cortisol levels were manipulated by administration of a single intravenous dose of hydrocortisone or saline solution, on separate days, to study changes in corticospinal and motor cortical excitability.

Progesterone - new therapy in mild carpal tunnel syndrome? Study design of a randomized clinical trial for local therapy.

Background: Local corticosteroid injection for carpal tunnel syndrome (CTS) provides greater clinical improvement in symptoms one month after injection compared to placebo but significant symptom relief beyond one month has not been demonstrated and the relapse of symptoms is possible.Neuroprotection and myelin repair actions of the progesterone was demonstrated in vivo and in vitro study.We report the design of a randomized controlled trial for the local injection of cortisone versus progesterone in "mild" idiopathic CTS.

Evidence for two concurrent inhibitory mechanisms during response preparation.

Inhibitory mechanisms are critically involved in goal-directed behaviors. To gain further insight into how such mechanisms shape motor representations during response preparation, motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) and H-reflexes were recorded from left hand muscles during choice reaction time tasks. The imperative signal, which indicated the required response, was always preceded by a preparatory cue.

Role of Renshaw cells in amyotrophic lateral sclerosis.

In this article the role of Renshaw cell involvement in experimental amyotrophic lateral sclerosis (ALS) is discussed, with an emphasis on the anatomy, physiology, and possible role in motor control of Renshaw cells. These cells are located in lamina VII of the spinal cord, are excited by motor axon collaterals, and inhibit homonymous and synergistic motoneurons in a negative-feedback fashion (recurrent inhibition). Early dysfunction and/or loss of Renshaw cells has been suggested to occur in experimental ALS, and the hypothesis has been put forward that this may be the event that makes motoneurons more susceptible to glutamatergic toxicity in ALS.

Prulifloxacin as a trigger of myasthenia gravis.

Fluoroquinolones has been rarely associated with exacerbation of myasthenia gravis (MG). We present a case of MG following a treatment with prulifloxacin, a new broad-spectrum oral fluoroquinolone. Fluoroquinolones of any generation may interfere with neuromuscular transmission and should be avoided in patients with MG.

A reappraisal of the central effects of botulinum neurotoxin type A: by what mechanism?

Botulinum neurotoxin A (BoNT/A) is a metalloprotease that enters peripheral motor nerve terminals and blocks the release of acetylcholine via the specific cleavage of the synaptosomal-associated protein of 25-kDa. Localized injections of BoNT/A are widely employed in clinical neurology to treat several human diseases characterized by muscle hyperactivity. It is generally assumed that the effects of BoNT/A remain localized to the injection site.

Anticipatory control of impending postural perturbation in elite springboard divers.

Among athletes, elite springboard divers (ED) should develop an optimal anticipatory control of postural stability, as a result of specific training. Postural strategies of ED and healthy subjects (HS) while expecting an impending perturbation were compared. The mean center of pressure (COP) position was analyzed during control quiet stance (cQS) and during anticipatory quiet stance (aQS(1-4)), i.

Effects of posture-related changes in motor cortical output on central oscillatory activity of pathological origin in humans.

Changes in shoulder position influence motor cortical outflow to Abductor Digiti Minimi (ADM) muscle in healthy humans. We examined whether these changes may affect finger tremor of central origin. Subjects had their shoulder positioned in two different configurations: 30 degrees horizontal adduction (ANT) and 30 degrees horizontal abduction (POST) with respect to neutral position at 0 degrees in the horizontal plane.

Dynamic changes in cortical and spinal activities with different representations of isometric motor actions and efforts.

Background: Positioning the shoulder joint from 30 degrees adduction (anterior [ANT]) to 30 degrees abduction (posterior [POST]) in the horizontal plane modifies the corticospinal output to hand and forearm muscles in humans.

Objective: We investigated the mechanisms by which the central nervous system (CNS) maintains force output under conditions of increased effort and reduced corticospinal activity.

Methods: Ten healthy subjects were studied with the shoulder joint fully supported and passively kept either in ANT or POST.

Memory formation in the motor cortex ipsilateral to a training hand.

Cortical reorganization within the primary motor cortex (M1) contralateral to a practicing hand has been extensively investigated. The extent to which the ipsilateral M1 participates in these plastic changes is not known. Here, we evaluated the influence of unilateral hand practice on the organization of the M1 ipsilateral and contralateral to the practicing hand in healthy human subjects.

Factors influencing the relation between corticospinal output and muscle force during voluntary contractions.

The mechanisms by which voluntary forces of different strengths are produced in human muscles are not clear. We studied the relation between force and surface electromyography (sEMG) variables over a wide range of voluntary contraction strengths of biceps brachii (BIC) and abductor digiti minimi (ADM). The relation between force and motor evoked potentials (MEPs) to transcranial magnetic stimulation of motor cortex was also assessed.

Heightened seizure susceptibility associated with brain dermoid cyst and the administration of human chorionic gonadotropin (hCG).

It is known that the intramuscular injection of human chorionic gonadotropin (hCG) lowers the threshold for motor evoked responses (MEPs) in the first dorsal interosseous (FDI) muscle to transcranial magnetic stimulation (TMS) in humans. We describe the case of a patient with a clinically silent left-sided nasofrontal dermoid cyst who, while being treated with hCG/LH for hypogonadotropic hypogonadism, presented with simple partial seizures, ipsilateral to the cyst, with secondary generalization. Motor cortex excitability was studied by single and paired TMS and MEPs were recorded from FDI.

Intermanual Differences in movement-related interhemispheric inhibition.

Interhemispheric inhibition (IHI) between motor cortical areas is thought to play a critical role in motor control and could influence manual dexterity. The purpose of this study was to investigate IHI preceding movements of the dominant and nondominant hands of healthy volunteers. Movement-related IHI was studied by means of a double-pulse transcranial magnetic stimulation protocol in right-handed individuals in a simple reaction time paradigm.

Spinal use-dependent plasticity of synaptic transmission in humans after a single cycling session.

The spinal cord is able to express use-dependent plasticity, as demonstrated in spinalized cats following treadmill training. In humans, spinal use-dependent plasticity is inferred from modifications in the size of H reflex, which are often more prominent after skilled motor training. Plasticity can develop at synaptic connections between afferent fibres and/or descending tracts and motoneurones or interneurones interposed in the spinal pathways.

Is the human masticatory system devoid of recurrent inhibition?

The aim of the present study was to investigate the existence or otherwise of a functional recurrent inhibitory system (Renshaw cell system) in the motoneurons that innervate human masticatory muscles. In a previous study, L: -acetylcarnitine (L: -Ac), a substance known to potentiate recurrent inhibition in humans was found to alter, in a specific way, the discharge variability, and the synchronous activity of motor units depending on the presence or absence of recurrent inhibition in the corresponding motoneuron pool. Using a similar paradigm, we have recorded the tonic discharge activity of motor unit pairs from the masseter muscle during voluntary isometric contraction while subjects were undergoing continuous intravenous saline (SAL, NaCl 0.